The present invention relates to the field of communications, specifically wireless communications. More specifically, the present invention relates to call admission control in third generation wireless systems.
Third generation wireless communications, such as wideband code division multiple access time division duplex (WCDMA-TDD) systems, will support not only voice service, but also a wide range of broadband services, such as video and Internet traffic. In such a system, the goal of call admission control is to guarantee that the quality of service (QoS) is met for all users admitted into the system. Call admission control directly affects the QoS of mobile users, and the stability and capacity of the system. Therefore, call admission control is very important for the design of WCDMA-TDD systems.
In recent years, there have been some advances regarding call admission control in WCDMA-FDD systems but few in WCDMA-TDD systems. One such system addresses the problem by making resource allocation based on a fixed required signal to interference ratio (SIR). In WCDMA-TDD systems, however, the required SIR of a user is not fixed and, in contrast, changes with time because of imperfect power control. In WCDMA-FDD systems, there are no timeslots whereas in WCDMA-TDD systems a user can use more than one timeslot.
A need therefore exists for providing call admission control for TDD systems.